Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


HDG Reinf in contact with Black Reinf

HDG Reinf in contact with Black Reinf

HDG Reinf in contact with Black Reinf

Does anyone have any information on the use of HDG reinforcing in contact with non-coated bars?

This is related to bridge deck bottom reinforcing.


RE: HDG Reinf in contact with Black Reinf

Thanks, Hokie...

The issue is non galv bars in a precast girder having galvanised bottom rfg in contact... lots of concrete cover and the bridge deck would likely work in the event the bottom rfg disappeared at the support.


RE: HDG Reinf in contact with Black Reinf

In the event of loss of protection by the alkaline concrete, the situation as described would tend to make the zinc corrode faster.  The zinc would still be effective, just not for as long.  With galvanizing, loss of the zinc does not cause a local corrosion acceleration of the steel similar to that which occurs with damage to epoxy coated bars.  

RE: HDG Reinf in contact with Black Reinf

I have not read the link provided by Hokie, but it is correct to say that the galvanizing will work to protect not only the coated bars, but also the uncoated bars in some cases.

It is generally preferred to use the same materials throughout to reduce corrosion where there may be differential alkalinity and chloride ion concentrations between the top and bottom bar locations.  One of the reasons top bars can corrode faster is the grounding of electrons through the bottom bars, allowing the top bars to corrode by way of a macrocell.  NEVER use epoxy bars in combination with uncoated bars for this reason.

RE: HDG Reinf in contact with Black Reinf

@dik: Not directly related to your OP.
ACI Chapter 12 gives coating factor for uncoated reinforcement and epoxy-coated bars. What coating factor would you use to determine the development and splice lengths of HDG bars?

RE: HDG Reinf in contact with Black Reinf

1.0...HDG doesn't affect the development.

RE: HDG Reinf in contact with Black Reinf

@hokie66: Thank you.

RE: HDG Reinf in contact with Black Reinf

It's not an issue with the coating factor... it's the discontinuity that causes the concern.  The application is bottom slab bars over a girder support... the girder shear connectors are not HDG and the slab steel is... it's the point of contact of the two items.

The rebar located on the bottom is less likely to experience carbonation and the chloride intrusion will be minimal. I wasn't concerned about it, but some others were.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close